Latch needles



April 1969 5. w. BEIGHTON ET AL 3,439,729

LATCH NEEDLES Sheet Filed Oct. 11, 1966 April 22, 1969 G. w. BEIGHTON ET AL 3,439,729

LATCH NEEDLES r of 2 Sheet Filed Oct. 11, 1966 United States Patent Office 3,439,729 LATCH NEEDLES George William Beighton, Groby, England, and Arthur Iden Britcher, Antrim, Northern Ireland, assiguors to T. Gr'eve and Company Limited 1 Filed Oct. 11, 1966, Ser. No. 585,855

65 l rrorit a pllcatlon Great Britain, Dec. 8, 19 C anus p p 51,970/65 Int. Cl. B21g 1/00 US. Cl. 163-5 4 Claims ABSTRACT OF THE DISCLOSURE spindle.

This invention concerns latch needles, such as are commonly employed, for example, in knitting mach1nes and other machines performing a thread-looping operation. Latch needles are well known and comprise a stem or shank formed at one end or at each end with a hook, at a region adjacent to which hook the stem is slotted longitudinally to provide a cleft between two side walls or cheeks; a latch is pivoted in this cleft by a pivot which extends across the cleft between the two cheeks through a pivot hole in the latch, the latch being prvotably movable between an attitude in which its free end engages the tip of the hook to close the latter and an attitude m which it extends substantially lengthwise of the stem away from the hook.

In a known construction the pivot for the latch 1s a tiny spindle having its ends engaged in holes in the two cheeks, and it has been common practice to thread the holes 1n the cheeks and to slightly countersink them at their outer ends, on each side of the needle; after locating the latch between the cheeks the threaded spindle is screwed into them and extends through the pivot hole in the latch; the ends of the spindle are then submitted to a riveting action so they are spread and fill the countersinks at each side of the needle. Finally it is necessary to grind each side of the needle to clean up the spindle ends and to ensure that they are flush with the sides of the needle.

This method of mounting a latch has certain disadvantages in so much as with the repeated oscillation of the latch towards and away from its closure attitude the spindle tends to work loose in the cheeks, and this causes a circular crack to appear at the ground sides of the needle. The loosening of the spindle causes rapid deterioration in the functioning of the latch and the circular cracks tend to damage the fibres of the textile yarns on which the needles may be employed. Additionally the extra operation of grinding each side of the needle merely causes the ends of the spindle to lie flush and adds to the time and cost of production and also involves an undesirable local removal of metal from the cheeks.

It is one object of this invention to overcome or reduce the aforesaid disadvantages by providing a method of manufacturing a latch needle in which the latch spindle is positively prevented from working loose and in which the ends of the spindle are sunk below the side faces of the needle, thus obviating the need for grinding. It is a further object of the invention to provide an improved latch needle in which the cheeks are tied together by the latch spindle, thus positively retaining the latch, and yet also having the appearance and certain advantages of 3,439,729 Patented Apr. 22, 1969 other latch needles of which is known as the impressed rivet type in which the latch pivot is provided by metal punched inwards from cheeks into the hole of the latch to form a bearing for the latter.

The invention provides a latch needle wherein the pivot for the latch is a spindle having its ends engaged in holes in the two side walls or cheeks, at least one end of the spindle has a keyed connection with its hole, the outer ends of the holes are enlarged and the extremities of the spindle are correspondingly enlarged by deformation, and the end surfaces of the spindle lie within said enlarged parts of the holes below the outer faces of the cheeks. By a keyed connection is meant a form of connection which prevents rotation of the spindle by virtue of a noncircular sectional shape of engaging regions of the spindle and hole.

It will be appreciated that in this needle not only is the spindle positively prevented from rotation, but it operates to tie together the cheeks of the needle thus preventing them from spreading apart and also adequately retaining the latch, and the necessity of grinding the outer faces of the cheeks is obviated since the end surfaces of the spindle lie below them and there is no danger that these spindle surfaces will damage the fibres of textile yarns.

Preferably each end of the spindle has a keyed connection with its hole. It is also preferred that the keyed connection or each of them shall be provided by forming the engaging regions of the spindle and hole with a polygonal cross-section. A suitable polygonal cross-section is octagonal, but other polygonal shapes may be employed.

Desirably at least one end of the spindle is screwed into its hole. This ensures the axial location of the spindle while its ends are being deformed. In practice it will be found most convenient to screw the spindle into both holes.

Preferably the regions of engagement of the spindle and hole are tapered inwardly. This permits the spindle to be readily deformed so as to conform to and lit a previously deformed non-circular region of the hole.

It is further preferred that the enlargement of the outer end of each hole shall be constituted by a countersink. The end of the spindle may readily be deformed as in a riveting operation to occupy this countersink, and the resultant rivet head has an adequate strength.

According to another desirable feature the included angle 0f the countersink is greater than that of the tapered engaging regions.

The invention also provides in the production of a latch needle wherein the pivot of the latch is a spindle having its ends engaged in holes extending through the two cheeks, the steps of providing the holes in at least one cheek with a region of noncircular cross-section and an enlarged outer end, positioning a short spindle in the holes with the latch mounted on it within the cleft, and deforming the spindle and thereby causing it to conform to the noncircular cross-section, its end to be enlarged occupy the enlarged ends of the holes like rivet heads, and its end surfaces to lie below the outer faces of the checks. Preferably, the hole is drilled after the shank is slotted to receive the latch.

The method may comprise forming coaxial indentations of noncircular cross-section, one in each face of the shank, by a punching operation effected prior to the shank being slotted to receive the latch, drilling a hole through the shank coaxially with and connecting the indentations, and enlarging the outer ends of the indentations.

-In order that the invention may be better understood reference will now be made to the accompanying drawings, in which:

FIGURE 1 is a front elevation of a needle according to this invention drawn to an enlarged scale;

FIGURE 2 is a side view of the same needle; while FIGURE 3 is a sectional view taken on the line A-A of FIGURE 2 and drawn on a further enlarged scale.

The shank of the needle is shown at 1. It is slotted longitudinally at 2 to provide a cleft between side cheeks 1a, 1b, which provide bearing faces between which the latch 3 is pivotally mounted in the cleft. At one end the needle is provided with a hook 1c, and the latch 3 having the usual spoon 3a at its free end is movable about a pivot spindle 4 between a hook-closing attitude in which the spoon 3a engages the extremity of the hook 1c and an open attitude in which as shown in FIGURES 1 and 2 the latch extends substantially lengthwise of the needle away from the hook.

A typical sequence of operations in the manufacture of the illustrated needle is as follows:

Before the shank is slotted at 2, the shank is subjected to a simultaneous punching operation at each side at the exact location for the latch spindle 4. The two punches 5, FIG. 3, are of truncated conical form and their tapered portion is of octagonal or other polygonal cross-sectional shape. The operation of these punches thus forms in each side of the needle a truncated conical indentation of polygonal cross-section.

The slot 2 is then cut in the shank, and the next step is to drill a hole through the shank using one of the punched indentations as a location. After drilling, the outer end of each hole is countersunk as shown at 6 in FIG. 3. The latch is then positioned in the slot and the remaining parallel portions 7 of the hole are then tapped with an appropriate fine screw thread.

It will be observed that each hole not only has a short inner length (at 7) which is screw threaded, but an intermediate region 9 which has a polygonal cross-section determined by the cross-sectional shape of the punch and an outer portion which is countersunk at 6, and it will be observed that the included angle of the countersink is greater than that of the region 9.

After withdrawal of the tap, the next operation is to screw a threaded spindle 4 (with the latch still in position) through the holes in the cheeks 1a, 1b so as to pass through the pivot hole in the latch. This is desirably effected by screwing a threaded piece of wire into the holes and then cutting off a length appropriate for the spindle. The ends of the spindle are trimmed off to allow an appropriate amount of the spindle to project beyond the outer face of each cheek. The amount of projection is kept within extremely fine limits because the final operation is to apply pressure to both ends of the spindle so as to compress the spindle ends longitudinally and expand them sectionally until they fill the polygonal region 9 and form domed countersunk rivet heads 8 which are sunk below the outer faces of the cheeks.

It will be appreciated that because a threaded spindle is used the trimming of the ends of the spindle and the riveting of the ends can be achieved without fear of axial displacement of the spindle. The fact that the ends of the spindle are screwed into both cheeks has the advantage that the riveting operation can be carried out without fear of squeezing the cheeks 1a, 1b in to nip the latch 3 unduly.

The hook is formed either before, or after, the insertion of the latch and spindle but preferably after slotting.

It will be appreciated that the above described method of providing a pivotal bearing for the latch has many advantages. Because of the octagonal or other polygonal tapered form into which parts of the ends of the spindle are compressed the spindle is positively prevented from rotation. Also by providing the countersinks 6 at each side of the needle shank, into which the ends of the spindle are also compressed like rivet heads, the ends of the spindle are securely anchored in the cheeks and thus afford maximum resistance to spreading of the cheeks and ensuring minimum side plate of the latch. In addition, by utilising the operation of compressing the spindle ends as aforesaid to also create domes which lie just below the side faces of the needle the necessity of grinding the side faces is obviated. The slightly sunk and domed ends of the spindle afford a smooth run over for the yarn and given an improved appearance.

The sequence of operations hereinbefore described is carried out after the needle has achieved its final width and it is an important advantage that it is unnecessary to grind or otherwise machine the outer faces of the checks (thereby reducing their thickness) after the spindle has been fixed in position.

We claim:

1. The method of making a latch needle of the type having a shank with a hooked end, wherein the shank is slotted longitudinally to provide a latch-receiving slot between spaced side cheeks, with a latch spindle having its ends received in holes in the checks and extending across the slot, and a hook-closing latch pivotally mounted, within the slot on the spindle, comprising the steps of:

(a) screw-threading the hole in at least one cheek,

(b) providing the hole in at least one cheek with a region of noncircular cross-section,

(c) providing each hole with an enlarged outer end,

(d) positioning a screw-threaded latch spindle in the holes with the latch mounted on it in the slot, by screwing the spindle into the threaded hole,

(e) upsetting the spindle and thereby causing it to conform to the noncircular cross-section, its ends to occupy the enlarged ends of the holes like rivet heads, and its end surfaces to lie below the outer faces of the cheeks.

2. A method according to claim 1, in which the hole is drilled after the shank is slotted to receive the latch.

3. A method according to claim 2, which comprises forming coaxial indentations of noncircular cross-section, one in each face of the shank, by a punching operation elfected prior to the shank being slotted to receive the latch, drilling a hole through the shank coaxially with and connecting the indentations, and enlarging the outer ends of the indentations.

4. A method according to claim 1, wherein the recited manufacturing operations are carried out after the needle has achieved its final width.

References Cited UNITED STATES PATENTS 1,798,890 3/1931 Mayo et al 66122 X 2,767,566 10/1956 Parsons 60-122 FOREIGN PATENTS 7,954 6/ 1902 Germany. 1,159,585 12/1963 Germany.

GRANVILLE Y. CUSTER, JR., Primary Examiner.

US. Cl. X.R. 66-l22 mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 43g 72g Dated April 22, 1969 Inventor(s) George William Beighton and Arthur Iden Britcher It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3 line 23 change "cross-section" to -cross-sectional shape.-.

Column 4 line 7 change "plate" to --play- Column 4 line 12 change "given" to --give-.

slGNED AN'U SEALED NOV 181% (SEAL) Attest:

Edward M. Fletcher, Jr. AM E. 'SUHUYLER, JR-

Anesting Officer Connnissioner of Patents 

